Device for sharpening twist drills



May 15, 1956 E. NADELIN 2,745,228

osvxcs FOR SHARPENING TwIs'r DRILLS Filed May 25, 1953 2 Sheets-Sheet l lnven for:

May 15, 1956 E- NADELIN DEVICE FOR SHARPENING TWIST DRILLS Filed May 25, 1953 2 Sheets-Sheet 2 Fig.3

IHHHI ll Inven for:

.FLNadeZin I Attorneys 2 United a s 2,745,223 r p v n DEVICE FOR SHARPENING Twrsr nnnitsl Eugen Nidelin, Ebingen, Wurttemberg, Germany, assignor to Gottlieb( liihring, Ebingen, Wurttemberg, Germany I Application May 25, 1953, Serial No. 3573334 Claims priority, application Germany May-28, 1952" 11 Claims. (C1. 51-219 This invention relates to a'device for' sharpening twist 5 drills of any diameter, comprising an angularly shaped drill holding fixture which, in a manner known as such, is pivotable about an axle mounted onia sewa e; A f

vExperience has shown that 'the' 'o tpfmterseetion of theswivelling' axis with the axis df" the .twist' drill frnu's't be located at a certain distance x fro'm the grinding. wheel face, said distance varying in proportion with the diameter of the drill. Since this spatiallyllocated point of inter section is not accessible and cannot be measured, proper adjustment of the fixture may be effected only by a more: or less time consuming"trial-and-error. methodl I In drill sharpening devices of knowri type the drill holdg ing fixture is pivota-ble about an axis inclined "infrelation to the grinding wheel and fast with a carriage, 's'aid' drill" holding fixture being in addition adjustable transversely to the swivelling axis. g

The improvement provided by the present invention resides in the fact that the drill holding fixture comprises two parts of Which one is .s lidable ltransverselyf to the drill axis, the other being slidable in a direction with parallel the grinding wheel face. This provides properloca- :tion and support for the twist drill, so that even drillsof the smallest'size may be ground. According to a'further feature of the invention the pivot constituting the swivelling axis is .tiltable about an axis extending transversely to the latter and parallel to the grinding wheel facea'nd may be locked in any desired position. v i V T v According to a further feature of the invention thetilting pivot is mounted on a cross slide rest shiftable "at right angles to the grinding wheel face. I L z Another feature of the invention'consists in: that'the holders of the drill holding fixture are provided with calibrated scales-the graduations of which are chosen in such a manner that'thedistance x of the'point of'i'ntersec'tion from the grinding wheel face varies in proportion with the size of the'drill. I

According to a further feature of the inventionvan' adjusting pin is provided which is adapted to be inserted into the drill holding fixture and permits the setting of the device in relation to the grinding wheelby shifting the cross slide rest. This arrangement servesto adjust the device upon mounting a new grinding wheel or after dressing the wheel. a

Further features 'and advantages of the invention will be apparent from the following detailed description and the accompanying drawing which in a diagrammatic manner shows one embodiment of a drill grinder according tothe invention. In the drawing:

Fig. 1 is a side elevational view of a part of a drill grinder according to the invention, 6

Fig. 2 is a side elevational view of the drill sharpening device showing the device in more detail, r

Fig. 3 is asectional view on line III-III of Fig. 2 of the adjusting means for lateral adjustment of the drill supports, and J Fig. 4 is a view of the same means viewed from outside.

' ameter.

2,745,228 Patented May 15, 1 956 A shaftz journaled in the machinehousing 1 carries a} 5 brought about by means of a handwheel 28 through a worm 29, worm wheel 30 andchain or cable 31 or the like which is trained over two wheels 32 and 33 of which wheel 32 is fixedly connected to worm wheel 30. The

ends of chain 31 arefastened to a projection 34 of slide 4.v This height adjustment serves the purpose of adjusting the entire drill grinding device with respect to the stationary grinding disc at a certain height or to release the grinding disc for interchange.

on movable slide 4. Apivot 5 mounted on the cross slide rest 4' supportsa supporting member 6 on which is mounted a swivelling shaft 7 pivotally carrying anarm extending upwardly at an angle. On a laterally projecting lug 9 of the supporting member 6 is an adjusting screw 10 which permits of exactly setting the angular position of the swiv elling axis relative to thegrinding wheelv face, which angle is preferably 13 A transverse beam 11 comprising a handle 12.1 pm vided on [the upper end of arm 8 for the purposeof swivelling-the latter about the swivelling shaft '7. A holder 14 is retained in parallel alignment with the grinding wheel facebya pin and slot guide 13, 13a and is adjustable odsaid guide; by means of ,an adjusting screw14a-arranged at xthat en d of the transverse beam which is; nearer the grinding wheel. An angular grooved block 15which serves as a support for the front end of the drill is mounted on the lower endof the holder 14. In the support 15- is provided a calibrated adjusting pin 15a serving to efiect setting of the device at the proper distance from the grinding wheel by means of shiftable cross slide rest 4.

is slidably mounted in a longitudinal slot 16 provided in the right portion of the transverse beam 11. The pin 17 constitutes a guide for a holder 19 adjustable vertically in relation to the transverse beam by means of an adjusting screw 19a, and carrying a centering spindle 20 with aconical recess on the face thereof in which seat the end of the drill inserted into the support 15. The holder-'19 permits alignment of the spindle axis and the axis of the inserted drill. 1

In order to permit rapid setting of the device to the correct point of intersection of the center line of the drill and the axis of the device for each drill, in case-of grinding drills of different diameters, the two holders 1'4 and 19, are provided with calibrated scales 14b and 1% which are adjustablein relation .to a fixedmark on the;

transversebeam 11 and. the sliding member 18, respectively. x Due to the inclined positionof the holders 14, and 19 the graduations: of the two scales are so interrelated that upon setting of. the fixed marks to the same locked in position, all sizes of drills of'a certain diameter range intended for the device in question may be ground with said device, becausethe height adjustment of the support 15 and of the centering spindle 20 is effected parallel to the grinding wheel face, and the graduation of the scales is so chosen that the distance x requiredfor' H 7 Support body 4', is. mounted for horizontal adjustment on a horizontal guide V Pin'15a is secured toelement 15 by screws 15b passing through slightly elongatedholesin element has been adjusted in relaf drill diameters of this range is necessarily and automatically obtained, the adjustment being effected by-a set screw 26. For this purpose arm 8 the foot 81) of which has a slide guide 25 cooperating with the hub part 8a is equipped with a lateral projection 35 in which freely rotatable an adjusting screw 26 is journaled which we rounds the free end of the projection 35 by connectors 37 (Figs 3 and 4). The thread part of screw 26 engages in a thread 38 of the hub part 8a so that arm 8 upon rotation of screw 26 is displaced laterally of hub part 8a. By screws 25a which pass through slots in foot 812, arm 8 is releasable prior to adjustment and fixable after adjustment. By loosening the two securing screws 25a and turning screw 26, thus arm 8 can be displaced on hub part 8a to the right or left. This is necessary, if the normal rear grind angle of the drill is to be increased or decreased according to the material to be drilled or if the axle 7 with all accessories for grinding a lefthand drill is to be placed on the other side of support 41 and is fastened there on the other mounting bolt 5. For corresponding adjustment foot 8b has two marks L and R which are adjustable with respect to stationary graduation lines on the hub part. The upper marks L and R adjusted to their stationary lower scale lines make possible a normal rear grind at the drill point for right or left hand drills.

Differences in length of the particular drill-s are compensated for by means of the adjustable centering spindle 20, the amount to be ground off a drill being likewise controlled by means of this spindle.

In order that the lips of the drill will be approximately vertical when entering in contact with the grinding wheel during grinding a further means securing this vertical position is provided according to the invention. For this purpose a two-armed lever 22 is pivotally supported on a pin 21 fast with the transverse beam 11, an indexing wheel 23 provided on its periphery with a plurality of pins 24 of gradually decreasing diameter being rotatably supported on the shorter arm of said two-armed lever. These pins are adapted to engage, under the effect of a spring 22a one of the spiral flutes of the inserteddrill, in order to keep one of the lips of the latter in a vertical position during grinding. For grinding the second lip the indexing pin is retracted from the spiral flute by de-' pressing the longer arm of lever 22 and is inserted in the other spiral flute after the drill has been rotated through 180.

In order to be able to vary also the relief angle, the drill is to be given an unsymmetrical position in the g'rind-' ing cone. This is efiected by simply shifting the arm 8 carrying the drill holding fixture, on its hub part 822 longi- -tudinally in a guideway 25 extending inthe swivellin'g direction, the end positions being determined by a set screw 26.

The device described above has the advantage that it also permits grinding of twist drills with left-hand twist. For this purpose the device has-only to be attached to the opposite side of a cross slide rest, the direction of rotation of the grinding wheel has to be changed by means of a reversing switch and the drill holding fixture has to be'reset by shifting the arm 8 longitudinally in the guide way 25 until a mark provided on set a'rm comes into alignment with a mark for left-hand twist provided on the'hub' part 8a.

'I'claim: I

1. In combination, a grinding wheel presenting a flat grinding surface to which a drill point is to be presented for grinding, and a drill shaping" device comprising a shaft lying in a plane normal to'the' grinding surface and at an angle to said surface so that a' projection of its axis intersects said grinding surface at an acute anglela'holder mounted to swing on said shaft, a first adjustable carrier so that the axis of such drill intersects the axis of said shaft at a point spaced from the grinding surface, a second adjustable carrier, a centering spindle mounted on said second adjustable carrier, each of said carriers and the adjacent holder structure having indicia thereon whereby said carriers can be adjusted to accommodate drills of different diameters, said means to grippingly support the point end of a drill including a V-grooved block and a spring pressed 'pin extending into said V groove to engage the flute of a drill lying in sa id \(-gr oo v e. II I I I 2. The device ofclaim 1, in which the shaft on which the holder is pivotally mounted is mounted on a pivot at right angles to the plane of said shaft and parallel to the plane of the grinding surface whereby theholder may be adjusted to vary the angle at which the drill is presented to the grinding surface, or the holder may be tilted away from the grinding surface.

3. The device of claim 2, in which means are provided by-which the said, pivot may, bemove d parallel to itself to adjust the location of the holder with respect to said g'jinding surface. I I I II 4. The device of claim 3, in which a preset gaugepin is mounted on the holder whereby said holder maybe accurately spaced from said grinding surface by said m ans provided for moving said pivot parallel to itself.

5. The device of claim 1, wherein the holder coniprises a. be'atii portion lying at an ,acute ang'le to the said shaft, and wherein said adjustable carrier carrying the support for the point end of the drill is adjustable in a direction parallel to the plane of the surface of the grind ingmeans, and wherein the said s e'cond carrier is ad justable longitudinally of said beam portion and also in a direction normal as saidbearn portion. I I I I 6."Th'e device of claim 5, wherein indicia is provided on each of the adjustable carrier means whereby the two carriers may be accurately set to accommodate drills of different sizes without recourse to measuring instruments.

7. The] device of clair'n l, wherein the saidspring pressed pin is mounted at one end of a two: armed spring actuated lever pivoted on the holder, the other end of said lever operating as a handle whereby the pinrrnay' be lifted to provide clearance an insertion or withdrawal of a drill.

8 The device of claim 7, I wherein the said pin is mounted on a rotatable head atthe end of said lever, and

wherein other similar pins" of different sizes are also" mounted in said rotatable head, whereby'the pin may be selected to agree in s'ize' were difill to' be sharpened. I

9.Th'e' device of claim 1, in which the holder is adjustable with regard to the shaft i a' direction parallel to' the pl'an of the surface'of the grinding means and normalto the'pla'n'e of'thfe shaft. I I I I 10. The device of claim 1, in which said holder is' i n' two partsconnected byan adjusting slide normal to the plane of said holder by means of which the plaiielof the axis of the drill may be moved in a direction normal to the plane of said holder to accommodate for right or lefthandtwistof dream. I j

11'; A grinding machine for twist drills'compri'sing' a frame, a horizontal sh'aft mounted in said frame, a grinding" wheel mountedoiif one end of: said shaft to present a radial grinding surface, a vertically sl idable carriage adju stably mounted on said frame below' said shaft, 21' horihoiit'al" slideway mountedjon s'a'id carriage afndextehdmg' beyond said'ra di'al grinding surface, a cros's'slide' adjustably mot-rated on". said' slidewa y, a horizontal pivot mounted on said cross slide, a supporting member p iv'-' otally mounted on said horizontal pivot, a swiveling shaft mounted on said support member and' ex ten'ding upwardly at an angle intersecting the plane of' sai d grinding surface, means to adjust the angle of intersection by pivotal movement of said support means onsaidjpivot', a'holder mounted for swiveling-movement on said swiveling shaft and having a" beani'lyin'g at an acute'angle to saidswivel ing shaft, a first carrier for the point end of a drill to be parallel to the said radial grinding surface when said beam is lying in a plane parallel to the vertical plane through said horizontal shaft, an adjustable second carrier mounted on said beam for the butt end of such a drill, each carrier and said holder having indicia thereon a gauge pin mounted in said first holder whereby the disl0 tance of said first holder to said grinding surface may be accurately set.

References Cited in the file of this patent UNITED STATES PATENTS 425,839 Walker Apr. 15, 1890 6 Hall *May 9, White Oct. 22, Williams Sept. 20, Young Dec. 29, Dixon Dec. 13, Wiken Feb.. 4, Smith et al. Oct. 25,

FOREIGN PATENTS Sweden Apr. 6, France Feb. 22, 

